Added new stats reporter to check suitable redis pool size

CHANGELOG.md

@@ -13,6 +13,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   Mojang API base addresses.
 - New health checker, that ensures that response for textures provider from Mojang's API is valid.
 - `dev` Docker images now have the `--cpuprofile` flag, which allows you to run the program with CPU profiling.
+- New StatsD metrics:
+  - Gauges:
+    - `ely.skinsystem.{hostname}.app.redis.pool.available`
 
 ### Fixed
 - Handle the case when there is no textures property in Mojang's response.

db/redis/redis.go

@@ -243,6 +243,10 @@ func (db *Redis) Ping() error {
 	return nil
 }
 
+func (db *Redis) Avail() int {
+	return db.pool.Avail()
+}
+
 func buildUsernameKey(username string) string {
 	return "username:" + strings.ToLower(username)
 }

db/redis/redis_integration_test.go

@@ -377,3 +377,8 @@ func (suite *redisTestSuite) TestPing() {
 	err := suite.Redis.Ping()
 	suite.Require().Nil(err)
 }
+
+func (suite *redisTestSuite) TestAvail() {
+	avail := suite.Redis.Avail()
+	suite.Require().True(avail > 0)
+}

di/db.go

@@ -1,8 +1,10 @@
 package di
 
 import (
+	"context"
 	"fmt"
 	"path"
+	"time"
 
 	"github.com/goava/di"
 	"github.com/spf13/viper"
@@ -23,6 +25,7 @@ var db = di.Options(
 	di.Provide(newRedis,
 		di.As(new(http.SkinsRepository)),
 		di.As(new(mojangtextures.UUIDsStorage)),
+		di.As(new(es.RedisPoolCheckable)),
 	),
 	di.Provide(newFSFactory,
 		di.As(new(http.CapesRepository)),
@@ -43,6 +46,12 @@ func newRedis(container *di.Container, config *viper.Viper) (*redis.Redis, error
 		return nil, err
 	}
 
+	if err := container.Provide(func() es.ReporterFunc {
+		return es.AvailableRedisPoolSizeReporter(conn, time.Second, context.Background())
+	}, di.As(new(es.Reporter))); err != nil {
+		return nil, err
+	}
+
 	if err := container.Provide(func() *namedHealthChecker {
 		return &namedHealthChecker{
 			Name:    "redis",

di/handlers.go

@@ -74,6 +74,11 @@ func newHandlerFactory(
 		mount(router, "/api", apiRouter)
 	}
 
+	err := container.Invoke(enableReporters)
+	if err != nil {
+		return nil, err
+	}
+
 	// Resolve health checkers last, because all the services required by the application
 	// must first be initialized and each of them can publish its own checkers
 	var healthCheckers []*namedHealthChecker

di/logger.go

@@ -13,6 +13,7 @@ import (
 	"github.com/mono83/slf/wd"
 	"github.com/spf13/viper"
 
+	"github.com/elyby/chrly/eventsubscribers"
 	"github.com/elyby/chrly/version"
 )
 
@@ -95,3 +96,9 @@ func newStatsReporter(config *viper.Viper) (slf.StatsReporter, error) {
 
 	return wd.Custom("", "", dispatcher), nil
 }
+
+func enableReporters(reporter slf.StatsReporter, factories []eventsubscribers.Reporter) {
+	for _, factory := range factories {
+		factory.Enable(reporter)
+	}
+}

eventsubscribers/stats_reporter.go

@@ -1,6 +1,7 @@
 package eventsubscribers
 
 import (
+	"context"
 	"net/http"
 	"strings"
 	"sync"
@@ -19,6 +20,17 @@ type StatsReporter struct {
 	timersMutex sync.Mutex
 }
 
+type Reporter interface {
+	Enable(reporter slf.StatsReporter)
+}
+
+type ReporterFunc func(reporter slf.StatsReporter)
+
+func (f ReporterFunc) Enable(reporter slf.StatsReporter) {
+	f(reporter)
+}
+
+// TODO: rework all reporters in the same style as AvailableRedisPoolSizeReporter
 func (s *StatsReporter) ConfigureWithDispatcher(d Subscriber) {
 	s.timersMap = make(map[string]time.Time)
 
@@ -175,3 +187,24 @@ func (s *StatsReporter) finalizeTimeRecording(timeKey string, statName string) {
 
 	s.RecordTimer(statName, time.Since(startedAt))
 }
+
+type RedisPoolCheckable interface {
+	Avail() int
+}
+
+func AvailableRedisPoolSizeReporter(pool RedisPoolCheckable, d time.Duration, stop context.Context) ReporterFunc {
+	return func(reporter slf.StatsReporter) {
+		go func() {
+			ticker := time.NewTicker(d)
+			for {
+				select {
+				case <-stop.Done():
+					ticker.Stop()
+					return
+				case <-ticker.C:
+					reporter.UpdateGauge("redis.pool.available", int64(pool.Avail()))
+				}
+			}
+		}()
+	}
+}

eventsubscribers/stats_reporter_test.go

@@ -1,6 +1,7 @@
 package eventsubscribers
 
 import (
+	"context"
 	"errors"
 	"net/http/httptest"
 	"testing"
@@ -392,3 +393,30 @@ func TestStatsReporter(t *testing.T) {
 		})
 	}
 }
+
+type redisPoolCheckableMock struct {
+	mock.Mock
+}
+
+func (r *redisPoolCheckableMock) Avail() int {
+	return r.Called().Int(0)
+}
+
+func TestAvailableRedisPoolSizeReporter(t *testing.T) {
+	poolMock := &redisPoolCheckableMock{}
+	poolMock.On("Avail").Return(5).Times(3)
+	reporterMock := &StatsReporterMock{}
+	reporterMock.On("UpdateGauge", "redis.pool.available", int64(5)).Times(3)
+
+	ctx, cancel := context.WithCancel(context.Background())
+
+	creator := AvailableRedisPoolSizeReporter(poolMock, 10*time.Millisecond, ctx)
+	creator(reporterMock)
+
+	time.Sleep(35 * time.Millisecond)
+
+	cancel()
+
+	poolMock.AssertExpectations(t)
+	reporterMock.AssertExpectations(t)
+}